I can see a future pain point for the flex lane EB approaching 39/90 because it ends at the same place where the onramp from Stoughton Road is coming in. So there will be a spot here where essentially 6 lanes of traffic are pinching down to 3 with the 3 GP lanes and the flex lane on the Beltline plus a two-lane onramp. That's going to be a source of daily backups until WisDOT endeavors to add an aux lane between Stoughton Road and 39/90.
I must say, the new overhead BGS signage is much more helpful in being true to reality with the "arrow per lane" standard. EB approaching 39/90, the signage used to make it seem like only the left lane was the exit to go NB on 39/90 an only once one gets to the old SB bridge over 12/18 does one see that the middle lane is either/or. The new signs make this arrangement abundantly clear well before the gore, which I like.
Last night, on the way back from happy hour, crews were installing new BGS's around Todd Dr and VMS overheads were saying something to the effect of "Flex Lane Testing in Progress". Makes me think it'll be up and running right after the holiday.